They were not true to the original.
I've never watched the movie, but it looks like they were true to the original in so far as Achilles was a whiny little b*tch. Hector and Odysseus are the two best heroes of the story.
http://www.youtube.com/watch?v=XEZpYe261eYWatch it through look what achiles does.
Just pointing out that were you to watch it you would see a completely different story and one that was changed to keep the 'star' on film longer as it adds nothing to the story.
Eric Bana was a good pic for the Hector role.